Thermal Fogging

 

The purpose of this method is to introduce small volumes of the main substance (insecticide) in an efficient manner. The reason for the efficiency of this method is the decrease in the size of the particulate material. This ensures it remains suspended in the space so that it can reach every nook and cranny of the space being treated. The reason the material is required to stay suspended is to ensure maximum penetration.

In thermal fogging, this is guaranteed by the construction and operation of the machine. This machine consists of a small pressurized chemical tank, where the dilution of material is placed, a fuel tank, a combustion chamber, an air intake, and a resonator. The most common fuels used are pure oils (petrol, diesel) or aqueous mixtures containing glycol. The fuel along with the air is drawn into the combustion chamber where a spark ignites the mix creating the necessary fumes. The fumes are carried into the resonator, where the velocity of the fumes is increased. At the end of the resonator the pressurized chemical is introduced into the fumes. The entire mix begins to condense due to the change in temperature, forming the fog that we associate with this method. The particle size ranges from 1-50 µm

For multiple reasons, this method can only be used in outdoor areas for vector control, such as lakes, fields, farms, and parks.

Even though they can be used in areas that are heavily populated, there are precautions to be taken to ensure effectiveness and the safety of all those involved.

 

Pre-treatment:

ü  Vacate the area of any populace, including the animals (if possible).

ü  Do a thorough inspection of the area, look for any potential area of higher contamination, or pest/insect breeding.

ü  Ensure the chemical used is appropriate to the task being used for.

ü  Ensure all handlers are wearing non-chemically reactive gloves, safety boots, coveralls, and respirator masks.

ü  Make sure the client is aware of the precautions to be taken to prevent exposure.

ü  If fogging treatment is being conducted for Vector control over a large area, it might be best to have a combined approach of multiple foggers working the area at the same time. This will ensure that the insects do not migrate from one sector to other.

ü  It should be noted that using an external treatment plan will not affect any contamination indoors. That is to say, the fog will not penetrate the interiors of building, so a separate treatment of the interiors will need to be carried out, if internal contamination is noted during the inspection phase.

ü  If using an oil-based fuel source, ensure there are no ignition sources around except the machine itself.

ü  Pretreatment safety measures must include advance notice to residents with scheduled date and time of treatment.

ü  Posting advisories to keep the windows and doors closed, prevent children and pets from pesticide exposure.   

ü  Wind direction and target area must be assessed to plan the treatment and area of exposure as the fog might drift with wind.